Apparatus for flat surface superfinishing



1967 TOSHIO ASAEDA ETAL 3,300,907

APPARATUS FOR FLAT SURFACE SUPERFINISHING Filed May 13, 1964 4 Sheets-Sheet 1 INVENTORS Tosmo nsnEM RYO 5mm; THIJHyOsHI Hmmva BY WMWW ATTORNEY 1967 TOSHIO ASAEDA ETAL 3,300,907

APPARATUS FOR FLAT SURFACE SUPERF-INISHING Filed May 15, 1964 4 Sheets-Sheet 2 4 A W f v9 la I I[ T2 II l3 Z I INVENTOR8 Tosu/o H HED Rv0 59KB! THDHYOSHI H RE/V0 ATTORNEYS 9 TOSHIO ASAEDA ETAL 3,300,907

APPARATUSFOR FLAT SURFACE SUPERFINISHING Filed May 13, 1964 4 Sheets-Sheet s INVENTORS T0 5/1/0 ASREDH R /0 5H KAI Tao/was; H/RHNO BY WW W ATTORNEYS ,1 TOSHIO ASAEDA ETAL 3,300,907

APPARATUS FOR FLAT SURFACE SUPERFINISHING Filed May 13, 1964 1 v 4 Sheets-Sheet 4 INVENTORS" TOSH/O H 5950A Rw/O 5H KAI TH DA IOSHI HIKHNO BY WWW ATTORNEYS United States 3,300,907 APPARATUS FOR FLAT SURFAQE SUPERFENHSHING Toshio Asaeda, 18 Tamagawa Kaminoge, Setagaya-ku,

Tokyo, Japan, Ryo Sakai, Sakura-Mura Niihari, Ibaragiken, and Tadayoshi Hirano, Koganei-shi, Tokyo, .Fapan; said Sakai and said Hirano assignors to said Asaeda Filed May 13, 1964, Ser. No. 367,150 Claims priority, application Japan, Sept. 27, 1963, (utility model) 38/ 72,500 3 Claims. (Cl. 51-124) This invention relates generally to apparatus for flat surface superfinishing, and particularly to means for producing a composite vibration.

Different kinds of machines for flat surface superfinishing are known which are devices adapted for use in producing smooth and accurate surfaces on metal articles. Such machines generally comprise a very fine grain disc-shaped abrasive stone that rotates in its own plane, means which is adapted to elastically hold work material against the surface of the disc-shaped abrasive stone with low pressure, and means by which work material is caused to vibrate on the contact surface relative to the rotational motion of abrasive grains. In the conventional type of fiat surface superfinishing machines, it has been customary to use an oscillation mechanism composed of a lever and an eccentric member which are adapted to impart to work material an oscillation around a fixed support.

It is widely known that the quality of superfinished surfaces is better When the path pattern left on the superfinished surfaces by abrasive grains are not oriented in one direction; in other words, the more complicated the path pattern is, the higher is the degree of superfinished surface. One of the features of the present invention is to provide means for producing a composite vibration made of two vibrations of different frequencies, which will impart such motion to the abrasive stone as to produce a complicated path pattern on superfinished surfaces, so that in combination with the rotation of the abrasive stone and the rotation of the work holder, the abrasive stone will be enabled to develop a multidirectional motion whereby a high degree of precision work will be achieved.

In Japanese Patent No. 313,398, there is advantageously arranged means for automatic sizing of the superfinished article in apparatus for fiat surface supe'rfinishing, where by the superfinished surface will have a uniform thickness and the article having such a surface will be brought to a predetermined degree of thickness, superfinishing operations being automatically stopped when such degree of thickness has been attained. This aim is achieved by providing two annular rings, which are mounted around the outer peripheral edge and inner peripheral edge of the disc-shaped abrasive stone respectively, and an annular ring designed for use in regulating the thickness 'of superfinished articles which is mounted around the outer peripheral edge of the work holder said annular ring for regulating the thickness of superfinished articles being disposed in such a way that the outer ring and the inner ring mounted on the disc-shapd abrasive stone come within the radius of thickness regulating ring. This arrangement makes it possible to use suitable material, such as ferro-alloy, nonferrous-alloy, or plastics, as the case may be, for fabricating the outer and inner rings of the abrasive stone and the thickness regulating ring, eliminating the necessity of using expensive material such as diamond, for regulating the production of accurate dimensions. Moreover, this arrangement overcomes the disadvantage inherent in the surface superfinishing machines of conventional type that, after the flat surface superfinishing of the article to a predetermined measure- 3',3%,%7 Patented Jan. 31, 1967 ment has been completed, the control member itself is subjected to the grinding action of the disc-shaped abrasive stone. By using surface superfinishing apparatus of this invention, a high degree of precision work can be achieved and the disturbance of the configuration of abrasive grains on the surface of abrasive stone brought about by the regulating member can be prevented from occurring.

The objects and features of the present invention will be better understood from the following description made with reference to the accompanying drawings where:

FIG. 1 is a front end view of the flat surface superfinishing apparatus of the present invention;

FIG. 2 is a longitudinal sectional view of FIG. 1;

FIG. 3 is a section taken along the line AA of FIG. 1;

FIG. 4 is a front vie-w of the composite vibration producing means;

FIG. 5 is a section taken along the line B-B of FIG. 4;

FIG. 6 is a diagram illustrating a composite vibration; and

FIG. 7 is a View, similar to FIG. 5, of another embodiment of the aforementioned composite vibration producing means.

In FIGS. 1 to 3, the apparatus is provided with a discshaped abrasive stone 1 and a holding plate 2 therefor, which are rotated by a shaft 3. There are also provided an outer rim 4 around the outer peripheral edge of said holding plate 2 and an inner rim 5 around the inner peripheral edge of said holding plate 2. Mounted face to face with the abrasive stone, in front thereof, is a lever 6, one end of which is carried by a shaft 7 and the other end of which forms a fork-shaped portion 8 engaging the sleeve 10 to compositie vibration producing means mounted on a shaft 9 (FIG. 3). This composite vibration producing means is to be subsequently described. On the lever 6 is rotatably mounted a gear 11' having teeth 11, and on gear 11 is mounted a work holder 13 to which work material 12 is to be fixed. Four pins 13', equally spaced from one another and disposed on the outer peripheral edge of work holder in the radial direction, engage four guide slots 14 which are also spaced equally from one another and disposed in the axial direction on the inner peripheral edge of gear 11', so that holder 13 can be inclined and is axially movable within the gear 11'. The engagement of said pins 13' in guide slots 14 prevents the relative motion of holder 13 and gear 11' from occurring, with the result that the rotary motion of gear 11' constitutes the rotary motion of holder 13. A push rod 15 bears against the holder 13 with a roller 16 provided at the tip thereof, maintaining contact with said holder. The holder 13, which can be inclined and is axially movable within the gear 11' as aforementioned, is caused to bring its surface into abutting contact on all phases with the surface of abrasive stone 1, for pressure is applied to the holder by the push rod through roller 16, said rod 15 being carried by a shaft which is fixedly secured to an actuating rod 17 engaging a rod 19 which is backwardly biased by a spring 18 as shown in FIG. 3. A driving shaft 21 mounted concentrically with the shaft 7 of lever 6 transmits rotation to gear 11 through gears 22 and 23.

In FIGS. 4 and 5 a shaft 9 which carries at the end thereof an eccentric shaft 32 having an eccentricity of 6 is rotatably mounted on the machine frame 33'. On this eccentric shaft 32 is rotatably mounted a gear 34 which meshes with the internal gear 35 secured to the machine frame 33. The eccentricity of extending boss 36 of gear 34 relative to the axial line of gear 34 or eccentric shaft 32 is 6 On this boss 36 is rotatably mounted a sleeve 10 which, as shown in FIG. 1, is engaged by the fork-shaped end portion 8 of lever 6.

Let the number of teeth of gear 34 be Z the number of teeth of internal gear 35 be Z and the number of revolutions of shaft 9 be N r.p.m., then the number of revolutions of N of shaft 34 can be expressed by the following formula:

In operation, the rotation of eccentric shaft 32 will cause lever 6 to develop a vibration with an amplitude of 261 and a frequency per minute of N At the same time, the rotation of eccentric boss 36 will cause lever 6 to develop a vibration with an amplitude of 262 and a frequency per minute of N Consequently, the vibration developed by lever 6 will be a composite of those two kinds of vibrations. This composite vibration is illustrated in the diagram of FIG. 6 in which abscissa is time t and ordinate is amplitude A.

If the internal gear 3-5 is caused to rotate at a suitable number of revolutions N r.p.m. instead of being fixedly secured to the machine frame 33, it will be possible to vary the number of revolutions N of gear 34 independent of the number of revolutions N of shaft 9. In this case, the number of revolutions N can be obtained from the following equation:

In FIG. 7 is illustrated a modification of the means shown in FIGS. 4 and 5. In this modification, there are provided a friction wheel 34 having a tire 34" mounted around the outer peripheral edge thereof and an internal cylinder 35 secured to the machine frame 33, in place of the gear 34 and internal gear 35. Let the outer diameter of tire 34 of friction wheel 34 be D and the inner diameter of internal cylinder 35 be D then the number of revolutions of friction wheel 34 can be obtained from the following formula which is obtained by substituting D and D for Z and Z respectively in the aforementioned formula:

If the internal cylinder 35 is caused to rotate at a suitable number of revolutions N r.p.m. instead of being secured to the machine frame, the number of revolutions of friction wheel 34 can be expressed by the following formula obtained from the corresponding formula set forth above.

As this modification does without a gear and an internal gear, it costs less to produce and has the advantage of preventing operational noises from generating.

Description will be continued with further reference to FIG. 1 and particularly to FIG. 2. Means is provided for dressing and maintaining the surface of disc-shaped abrasive stone 1 in its original perfectly flat condition by a conditioning grinding wheel 24 and a thickness regulating ring 31. The cup-shaped conditioning grinding Wheel 24, the diameter of which is such that the outer ring 4 and the inner ring of disc-shaped abrasive stone 1 come within the radius of said conditioning grinding wheel 24 is carried by a driving shaft 25 which is rotatably mounted on the bearing box 26 slidably mounted on the sleeve 27 of machine frame 33. There is provided between the flange 26 of said bearing box 26 and the machine frame 33 a compression spring 28 which causes,

by its biasing force transmitted through the bearing box 26 and shaft 25, the conditioning grinding wheel 24 to bear against the disc-shaped abrasive stone 1. The rotation of motor 29 shown in FIG. 3 actuates the driving shaft 25 through belt 30. Thus the conditioning grinding wheel 24 is caused to rotate while bearing against the disc-shaped abrasive stone 1, the former dressing the surface of the latter so as always to maintain said surface in a perfectly flat plane. As shown in FIG. 2, the diameter of conditioning grinding wheel 24-, being such as to bring the outer ring 4 and the inner ring 5 of the disc-shaped abrasive stone within the radius of said conditioning grinding wheel 24- grinds the face of the disc-shaped abrasive stone as Well as the outer and inner rings 4 and 5 thereof, so that the face of the disc-shaped abrasive stone and the outer and inner rings are always maintained in the same plane and in a perfectly flat and smooth plane.

Around the outer peripheral edge of work holder 13 is mounted a thickness regulating ring 31, the thickness of which is such that the distance between the upper surface of said ring and the surface of work holder 13 is equal to the desired value of thickness t to which the particular article 12 is to be brought. If the thickness of the particular article 12 before superfinishing operation is t as shown in the drawings, t't represents the amount of material to be removed by the operation. When the superfinishing operation progresses, bringing t nearer to t and ultimately equal to t, the thickness regulating ring 31 moves into contact with both the outer ring 4 and inner ring 5 of disc-shaped abrasive stone 1 and the superfinishing operation is automatically terminated because the pressure applied to the holder 13 through roller 16 ceases to be applied to the article 12 on the holder. In other words, the automatic termination of operation takes place. The only thing necessary to do to perform a flat surface superfinishing operation on articles having a variation in thickness r is to substitute one thickness regulating ring for another.

Although this invention has been disclosed and described in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention.

Having thus described the invention, the following is claimed new and novel and upon which Letters Patent is desired:

1. Flat surface superfinishing apparatus comprising, in combination, a very fine grain disc-shaped abrasive stone; means rotatably mounting said stone for rotation about its axis; a lever extending perpendicular to the axis of said stone; means pivotally supporting one end of said lever for oscillation of said lever in a plane parallel to the Working face of said stone, the free end of said lever being forked; a work holder mounted on said lever intermediate the ends thereof and adjacent the working face of said stone; means biasing said work holder toward said stone; and driving means operatively associated with the forked end of said lever and operable to impart a composite oscillation to said lever, comprising two superposed oscillations; said driving means including a drive shaft mounted for rotation about an axis substantially parallel to the axis of said stone, a smaller diameter stub shaft extending eccentrically from the end of said drive shaft, an intermediate wheel eccentrically mounted on said stub shaft for free rotation thereon and having a disc portion and a smaller diameter hub portion, said hub portion be ing irotatably engaged in said forked end of said lever, and a ring member, of larger diameter than said wheel disc portion, surrounding said wheel disc portion for rolling of the latter around the inner surface of said ring member as said drive shaft rotates; whereby said lever, due to the eccentricity of said stub shaft, has a relatively small oscillation imparted thereto at a relatively high frequency and, due to the eccentricity of said intermediate wheel on said stub shaft and the rolling of said intermediate wheel about said ring member, has a relatively large oscillation imparted thereto at a relatively higher frequency.

2. Flat surface superfinishing apparatus, as claimed in claim 1, in which said disc portion of said intermediate wheel comprises a spur gear; said ring member being an internal ring gear.

3. Flat surface superfinishing apparatus, as claimed in claim 1, including a friction tire extending around said 10 disc portion of said intermediate wheel and frictionally engaging the inner surface of said ring member.

References Cited by the Examiner UNITED STATES PATENTS 1,326,129 12/1919 Chadbourne 74-52 2,181,318 11/1939 Fessenden 74-215 2,398,628 4/1946 DykOSki 51124 2,404,282 7/1946 Fruth 51-124 2,565,590 8/1951 Bullard 125--11.2

FOREIGN PATENTS 38/15545 8/1963 Japan.

HAROLD D. WHITEHEAD, Primary Examiner. 

1. FLAT SURFACE SUPERFINISHING APPARATUS COMPRISING, IN COMBINATION, A VERY FINE GRAIN DISC-SHAPED ABRASIVE STONE; MEANS ROTATABLY MOUNTING SAID STONE FOR ROTATION ABOUT ITS AXIS; A LEVER EXTENDING PERPENDICULAR TO THE AXIS OF SAID STONE; MEANS PIVOTALLY SUPPORTING ONE END OF SAID LEVER FOR OSCILLATION OF SAID LEVER IN A PLANE PARALLEL TO THE WORKING FACE OF SAID STONE, THE FREE END OF SAID LEVER BEING FORKED; A WORK HOLDER MOUNTED ON SAID LEVER INTERMEDIATE THE ENDS THEREOF AND ADJACENT THE WORKING FACE OF SAID STONE; MEANS BIASING SAID WORK HOLDER TOWARD SAID STONE; AND DRIVING MEANS OPERATIVELY ASSOCIATED WITH THE FORKED END OF SAID LEVER AND OPERABLE TO IMPART A COMPOSITE OSCILLATION TO SAID LEVER, COMPRISING TWO SUPERPOSED OSCILLATIONS; SAID DRIVING MEANS INCLUDING A DRIVE SHAFT MOUNTED FOR ROTATION ABOUT AN AXIS SUBSTANTIALLY PARALLEL TO THE AXIS OF SAID STONE, A SMALLER DIAMETER STUB SHAFT EXTENDING ECCENTRICALLY FROM THE END OF SAID DRIVE SHAFT, AN INTERMEDIATE WHEEL ECCENTRICALLY MOUNTED ON SAID STUB SHAFT FOR FREE ROTATION THEREON AND HAVING A DISC PORTION AND A SMALLER DIAMETER HUB PORTION, SAID HUB PORTION BEING ROTATABLY ENGAGED IN SAID FORKED END OF SAID LEVER, AND A RING MEMBER, OF LARGER DIAMETER THAN SAID WHEEL DISC 